1. Field of the Invention
The present invention relates to a battery charger for charging a battery pack formed so as to be attachable to a tool main body of an electric tool as a power source of the electric tool.
2. Description of the Related Art
In an electric tool such as a hand-held charging type driver, a battery pack is attached to the tool main body as the power source. This battery pack is detached from the tool main body and can be charged by a separate battery charger. When charging the battery pack by the separate battery charger, the battery pack is attached to the battery charger as well as to the tool main body. The battery pack is slidingly attached to the tool main body (hereinafter referred to as sliding attachment), and when the battery pack is charged by the battery charger, the battery pack is attached to the battery charger in the same way as it is attached to the tool main body (the same sliding attachment). For this purpose, as disclosed in Japanese Laid-Open Patent Application No. 2009-296724, the battery charger is provided with a guide portion extending in the sliding direction in order to guide a sliding attachment portion of the battery pack. Further, the above-mentioned guide portion is formed by resin molding, which means that it must be molded into a thin-walled shape so that it may not produce a sink mark at the time of resin molding. In view of this, in the prior art, a mold is applied to the guide portion from the inner side (lower side) toward the outer side (upper side) so as to reduce the thickness of the thick-walled resin portion (wall thinning), thus forming the guide portion as a thin-walled portion.
When an attempt is made to apply the mold to the guide portion from the inner side (lower side) toward the outer side (upper side), an opening communicating with the inner and outer sides of the case will be allowed to be formed in the opposing portion of the inner side (lower side) of the guide portion. Then, if some water is splashed onto the battery charger, the water may be allowed to enter inside of the case through the opening. In view of this, in such a case, a drainage path is provided so that the water can be drained without affecting functions of a built-in component, which may result in a rather complicated structure in an inner side of the case.
One way to simplify the structure in the inner side of the case is to apply a mold to the guide portion from the outer side (upper side) toward the inner side (lower side) so as to thin the thick resin wall from the outer side (upper side) of the guide portion, thereby forming the guide portion as a thin-walled portion.
However, an attempt to reduce the thickness of the thick resin portion from the outer side (upper side) of the guide portion would result in the outer (upper portion) of the guide portion being formed in a concave configuration. Then, due to this concave configuration, water would likely to be gathered and retained and dust would be likely to be accumulated on the outer side (upper side) portion of the guide portion.
Thus, there is a need in the art to provide a guide portion for sliding attachment of the battery pack as a part of a case by integral resin molding, and to form the guide portion as a thin-walled portion without having to provide an opening communicating with the inner and outer sides of the case, which can solve the problem of water retention and dust accumulation on the guide portion.